Apparatus for hot-dip coating strip



June 27, 1961 w. HARRIS EIAL 2,989,944

! APPARATUS FOR HOT-DIP COATING STRIP 1, Filed Sept. 10, 1959 2 Sheets-Sheet 1 IN VEN TORS ARC/v 14 HdfiaQ/S i all FfifD M 17490 June 27, 1961 A. w. HARRIS 'ErAL 2,989,944

APPARATUS FOR HOT-DIP COATING STRIP Filed Sept. 10, 1959 2 Sheets-Sheet 2 INVENTORS 4/?0/ 144 #429/5 g 441 250 14442.0

By Max?! ATTURNEY United States Patent APPARATUS FOR HOT-DIP COATING STRIP Arch W. Harris, Warrensville Township, Cuyahoga County, Ohio, and Alfred H. Ward, Brentwood, Pa.,

assignors to United States Steel Corporation, a corporation of New Jersey Filed Sept. 10, 1959, Ser. No. 839,142

4Claims. (Cl. 118-419) This invention relates to an improved apparatus for coatingmetal strip by a continuous hot-dip process.

Although our invention is not limited to any specific base metal or coating material, it is particularly applicable to coating steel strip with such metals as aluminum or zinc. One problem often encountered in this operation is that molten coating metal does not properly wet some areas of the strip surface, which thus remain uncoated. Failure of coating metal to wet strip is believed due to an oxide film which forms on the surface of the coating bath and tends to cling to strip entering the bath and prevent proper contact between the strip surface and the coating metal. It is known this tendency can be overcome or at least minimized by moving strip vertically into a bath, instead of at an angle inclined to the vertical, and by use of mechanical bafiles which extend into the bath where the strip enters and prevents the strip from contacting the oxide film.

An object of the present invention is to provide an improved bafiie construction and mounting which increase the effectiveness of the bafiles in preventing strip from contacting and picking up an oxide film and which also overcome any possibility of bafiles mechanically damaging the strip surface.

A further object is to provide an improved bafiie mounting of the foregoing type which enables the position of the baffles to be adjusted readily as to both their vertical position and their spacing from the strip surface.

A more specific object is to provide an improved baflle construction and mounting in which the baffles carry facings of graphite or other form of carbon adjacent the strip to avoid damaging the surface, and in which the bafiles are mounted on hangers adjustable both vertically and toward and away from the strip surface.

In accomplishing these and other objects of the invention, we have provided improved details of structure, preferred forms of which are shown in the accompanying drawings, in which:

FIGURE 1 is a diagrammatic vertical sectional view -of a coating apparatus equipped with our improved bafiies and mounting;

FIGURE 2 is an elevational view on a larger scale and with parts broken away taken in a plane transverse to those of the bafiies;

FIGURE 3 is a vertical section on line III-Ill of FIG- URE 2; and

FGURE 4 is a diagrammatic vertical sectional view of a modification.

FIGURE 1 shows a conventional receptacle which contains a bath B of molten coating metal, for example aluminum or zinc, heated by any conventional means, not shown, to maintain it in a molten state. Continuous strip S, for example steel, enters the bath through a closed chute 12 which extends below the bath surface. Commonly the strip comes directly from an annealing furnace, not shown, which has a nonoxidizing atmosphere, and the chute protects the strip surface against oxidation as the strip travels between the furnace and bath. In the embodiment FIGURE 1 shows, the strip travels vertically as it enters the bath and passes around two sink rolls 13 and 14 within the bath and between two coating rolls 15 as it emerges, all conventional. The

2,989,944 Patented June 27, 1961 strip acquires a coating as it passes through the bath and after leaving continues on to conventional finishing equipment.

As FIGURE 1 also indicates, the strip passes between two bafiies 16 and 17 located at the bath surface within chute 12. The purpose of these baflles is to prevent the strip from contacting and picking up oxide film which unavoidably forms on the bath surface. The baflles are constructed and mounted in accordance with our invention and are shown in more detail in FIGURES 2 and 3.

Our mounting includes plates 18 fixed to the end walls of chute 12 and preferably attached for horizontal adjustment on bolts 19 which extend through slots 20 in the plates. Each plate carries a first vertically aligned pair of guide loops 21 and a second vertically aligned pair of guide loops 22 horizontally offset from the first pair. Respective bars 23 and 24 are received in the two pairs of loops 21 and 22 for vertical adjustment. Bar '23 has an outwardly offset screw-threaded extension 25 at its upper end. Plate 18 carries a pair of vertically spaced brackets 26 which receive extension 25. A worm gear 27 is threadedly engaged with extension 25 and lies in the space between the two brackets 26. A bearing plate 28 is mounted on the side Wall of chute 12. A

worm 29 is journaled in bearings 30 and 31 carried by plates 18 and 28 and meshes with worm gear 27, whereby rotation of the worm rotates the worm gear and thus raises or lowers bar 23. Bar 24 is equipped with similar mechanism 32 to enable it to be raised or lowered.

A depending U-shaped hanger 33 is pivoted to the two bars 23 on opposite sides of chute 12 and extends into the bath beneath the chute. Battle 16 is formed on the central portion of the hanger and is dimensioned to extend about 12 inches into the bath, about 4 inches above the bath surface and 6 to 8 inches beyond the strip edges. The side of the bafile toward the strip carries a facing 34 preferably of graphite or other form of carbon, which the coating metal does not attack nor build up thereon. Graphite also is softer than the strip so there is little chance of damage to the strip surface by contact with the bafile. A screw-threaded block 35 is pivoted to the outside of hanger 33. A screw-threaded spindle 36 is engaged with said block and journaled in a bearing 37 carried by a plate 38 fixed to the side wall of chute 12, whereby rotation of spindle 36 adjusts the spacing between bafile 16 and the strip. In like manner baflle 17 is formed on a depending U-shaped hanger 39 pivoted to the other bars 24, and carries a similar facing 40. The spacing between baffle 17 and the strip can be adjusted through a mechanism 41, which is similar to the block 35, spindle 36 and bearing 37.

In operation, plates 18 are first adjusted with respect to chute 12 to center bafiles 16 and 17 about a plane tangent to the sink roll 13. Next the bafiles are adjusted vertically with respect to the surface of bath B, as already explained, and are spread apart. Strip S is threaded between the baflles, around the sink rolls 13 and 14, and up between the coating rolls 15. The bafiles are moved towrd the strip until their facings 34 and 40 contact the strip and then backed away sufficiently that the strip can run freely between them. The strip is then pulled continuously through the bath in the usual fashion to apply the coating. The bafiles efiectively prevent the surface of the strip from contacting and picking up oxide film from the bath surface. When the line is shut down, the baffles preferably are lowered to positions entirely beneath the bath surface.

FIGURE 4 diagrammatically shows a modification in which the strip S enters the bath at an angle inclined to the vertical. The chute 12 and baflies 16 and 17 are disposed at the same angle as the strip. The bafiles can be ing strip inherently has less tendency to drag along oxide,

but our bafiles also are effective when applied to a strip traveling at an angle inclined to the vertical. e While we have shown and described certain preferred embodiments of the invention, it is apparent that other modifications may arise. Therefore, we do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

We claim:

1. In an apparatus for applying a coating metal to the surface of a metal strip by a continuous hot-dip Process, said apparatus including a receptacle adapted to contain a bath of molten coating metal, means for guiding the strip through the bath, and an enclosed chute which extends into the bath and through which the strip enters, the combination therewith of a device for preventing the strip from contacting and picking up oxide film from the bath surface as the strip enters the bath, said de ice comprising a pair of bafiles located on'opposite sides of the strip within said chute and extending both above and below the bath surface, said baflies having facings which prevent attack by the coating metal, and means mounting said baffles for adjustment toward and away from the strip surface and toward and away from the bath surface.

2. In an apparatus for applying a coating metal to the surface of a metal strip'by a continuous hot-dip process, said apparatus including a receptacle adapted to contain a bath of molten coating metal, means for guiding the strip through the bath, and an enclosed chute which extends into the bath and through which the strip enters, the combination therewith of a device for preventing the strip from contacting and picking up oxide film from the bath surface as the strip enters the bath, said device comprising a pair of depending U-shaped hangers carried by said chute and extending across the chute therebeneath, respective baffles carried by said hangers on opposite sides of the strip within said chute and extending both above and below the bath surface, said baflles having facings which prevent attack by the coating metal, and means for adjusting said hangers to vary the positions of said bafiles toward and away from the strip surface and toward and away from the bath surface.

3. A combination as defined in claim 2 in which said chute and said bafiies are vertical.

4. A combination as defined in claim 2 in which said chute and said baflies are inclined to the vertical.

References Cited in the file of this patent UNITED STATES PATENTS Oganowski Nov. 24, 1959 

